Example: Follow Me Mode

This example demonstrates how to use the Follow Me plugin. It shows how to send the drone both the current position of the target (FollowMe::TargetLocation) and the relative position at which it should follow (FollowMe::Config).

Follow Me QGC Screenshot

A real application using this API will get the position information from the underlying operating system. The example uses a fake position source (FakeLocationProvider) to enable it to be run on computers that do not have position information. The FakeLocationProvider emulates the typical usage of common positioning APIs used in Android, Linux and iPhone.

Running the Example

Special notes for this example:

  • Before running this example you will need to install Boost libraries. For Linux this is done as shown below:
    sudo apt-get install libboost-all-dev
    
  • To use QGroundControl with this example you must ensure that GSC Position Streaming is disabled (otherwise QGC and the SDK will both send position updates and they will conflict). To do this use the latest QGC Daily Build and ensure that the Application Setting > General > Miscellaneous > Stream GCS Position is set to Never.

Otherwise the example is built and run in the normal way (as described here).

The example terminal output should be similar to that shown below:

This is from a debug build of the SDK. A release build will omit the "Debug" messages.

$ ./follow_me udp://:14540
[01:55:59|Info ] DronecodeSDK version: 0.2.8 (dronecode_sdk_impl.cpp:25)
Wait for system to connect via heartbeat
[01:55:59|Info ] New device on: 127.0.0.1:14580 (udp_connection.cpp:200)
[01:55:59|Debug] New: System ID: 1 Comp ID: 1 (dronecode_sdk_impl.cpp:286)
[01:55:59|Debug] Component Autopilot added. (system_impl.cpp:335)
[01:56:00|Debug] Found 1 component(s). (system_impl.cpp:462)
[01:56:00|Debug] Discovered 4294967298 (system_impl.cpp:464)
Waiting for system to be ready
...
Waiting for system to be ready
System is ready
Armed
[01:56:07|Debug] MAVLink: info: ARMED by arm/disarm component command (system_impl.cpp:273)
In Air...
[01:56:07|Debug] MAVLink: info: Using minimum takeoff altitude: 2.50 m (system_impl.cpp:273)
[01:56:07|Debug] MAVLink: info: Takeoff detected (system_impl.cpp:273)
[01:56:07|Debug] MAVLink: info: Using minimum takeoff altitude: 2.50 m (system_impl.cpp:273)
[FlightMode: Takeoff] Vehicle is at: nan, nan degrees.
[FlightMode: Takeoff] Vehicle is at: nan, nan degrees.
[FlightMode: Hold] Vehicle is at: nan, nan degrees.
[01:56:12|Debug] Waiting for the system confirmation of the new configuration.. (follow_me_impl.cpp:81)
[FlightMode: FollowMe] Vehicle is at: nan, nan degrees.
[FlightMode: FollowMe] Vehicle is at: 47.3977, 8.54559 degrees.
[FlightMode: FollowMe] Vehicle is at: 47.3977, 8.54559 degrees.
[FlightMode: FollowMe] Vehicle is at: 47.3976, 8.54559 degrees.
[FlightMode: FollowMe] Vehicle is at: 47.3976, 8.54559 degrees.
[FlightMode: FollowMe] Vehicle is at: 47.3976, 8.54559 degrees.
[FlightMode: FollowMe] Vehicle is at: 47.3975, 8.54559 degrees.
[FlightMode: FollowMe] Vehicle is at: 47.3975, 8.54559 degrees.
[FlightMode: FollowMe] Vehicle is at: 47.3974, 8.54559 degrees.
[FlightMode: FollowMe] Vehicle is at: 47.3974, 8.54559 degrees.
[FlightMode: FollowMe] Vehicle is at: 47.3974, 8.54563 degrees.
[FlightMode: FollowMe] Vehicle is at: 47.3974, 8.54567 degrees.
[FlightMode: FollowMe] Vehicle is at: 47.3974, 8.5457 degrees.
[FlightMode: FollowMe] Vehicle is at: 47.3974, 8.54574 degrees.
[FlightMode: FollowMe] Vehicle is at: 47.3974, 8.54577 degrees.
[FlightMode: FollowMe] Vehicle is at: 47.3974, 8.54581 degrees.
[FlightMode: FollowMe] Vehicle is at: 47.3974, 8.54588 degrees.
[FlightMode: FollowMe] Vehicle is at: 47.3974, 8.54592 degrees.
[FlightMode: FollowMe] Vehicle is at: 47.3974, 8.54595 degrees.
[FlightMode: FollowMe] Vehicle is at: 47.3974, 8.54595 degrees.
[FlightMode: FollowMe] Vehicle is at: 47.3975, 8.54595 degrees.
[FlightMode: FollowMe] Vehicle is at: 47.3975, 8.54595 degrees.
[FlightMode: FollowMe] Vehicle is at: 47.3975, 8.54595 degrees.
[FlightMode: FollowMe] Vehicle is at: 47.3976, 8.54595 degrees.
[FlightMode: FollowMe] Vehicle is at: 47.3976, 8.54595 degrees.
[FlightMode: FollowMe] Vehicle is at: 47.3977, 8.54595 degrees.
[FlightMode: FollowMe] Vehicle is at: 47.3977, 8.54595 degrees.
[FlightMode: FollowMe] Vehicle is at: 47.3977, 8.54595 degrees.
[FlightMode: FollowMe] Vehicle is at: 47.3977, 8.54592 degrees.
[FlightMode: FollowMe] Vehicle is at: 47.3977, 8.54588 degrees.
[FlightMode: FollowMe] Vehicle is at: 47.3977, 8.54581 degrees.
[FlightMode: FollowMe] Vehicle is at: 47.3977, 8.54577 degrees.
[FlightMode: FollowMe] Vehicle is at: 47.3977, 8.54574 degrees.
[FlightMode: FollowMe] Vehicle is at: 47.3977, 8.5457 degrees.
[FlightMode: FollowMe] Vehicle is at: 47.3977, 8.54567 degrees.
[FlightMode: FollowMe] Vehicle is at: 47.3977, 8.54563 degrees.
[FlightMode: FollowMe] Vehicle is at: 47.3977, 8.54563 degrees.
waiting until landed
[01:56:53|Debug] MAVLink: info: Landing at current position (system_impl.cpp:273)
waiting until landed
...
waiting until landed
[01:57:12|Debug] MAVLink: info: Landing detected (system_impl.cpp:273)
[01:57:12|Debug] MAVLink: info: DISARMED by auto disarm on land (system_impl.cpp:273)
Landed...

How it works

The example registers with FakeLocationProvider for location updates. These are passed to the Follow Me plugin, which in turn sends them to the vehicle.

The operation of the "SDK-specific" part of this code is discussed in the guide: Follow Me.

Source code

© Dronecode 2017-2020. License: CC BY 4.0            Updated: 2021-04-14 07:04:25

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